Bone china is a type of porcelain that is composed of bone ash. It has been defined as "ware with a translucent body", where Bone china is the strongest of the porcelain or china ceramics, having very high mechanical and physical strength and chip resistance, and is known for its high levels of whiteness and translucency. Its high strength allows it to be produced in thinner cross-sections than other types of porcelain.
In the mid-18th century, English potters had not succeeded in making hard-paste porcelain (as made in East Asia and Meissen porcelain) but found bone ash a useful addition to their soft-paste porcelain mixtures, giving strength. This became standard at the Bow porcelain factory in London (operating from around 1747), and spread to some other English factories.
The modern product was developed by the Staffordshire potter Josiah Spode in the early 1790s. Spode included kaolin, so his formula, sometimes called "Staffordshire bone-porcelain", was effectively hard-paste, but stronger, and versions were adopted by all the major English factories by around 1815.
From its initial development and up to the latter part of the 20th century, bone china was almost exclusively an English product, with production being effectively localised in Stoke-on-Trent.
Most major English firms made or still make it, including Fortnum & Mason, Mintons, Coalport, Spode, Royal Crown Derby, Royal Doulton, Wedgwood and Worcester.
In the UK, references to "china" or "porcelain" can refer to bone china, and "English porcelain" has been used as a term for it, both in the UK and around the world.
Source: https://en.wikipedia.org/wiki/Bone_china
